Protecting pensions, future funding of the NHS, and defence spending are all at risk if the UK votes to leave the EU, Prime Minister David Cameron and Chancellor George Osborne have warned.

The Prime Minister told the Sunday Telegraph that leaving the EU would put a “black hole in our public finances of between £20bn and £40bn.”

Cameron said that a Brexit would have a negative impact on pensioners and the NHS.

Cameron said that economic cost of a Brexit would threaten the “triple lock” mechanism currently used by the government for uprating the Basic State Pension (BSP), which is currently in line with whichever is higher – earnings, inflation or 2.5 per cent.

“We’ve made a special effort to protect pensioners,” the PM said. “We did all this in the expectation of a growing economy. But if we had a big black hole, we could struggle to justify this special protection any longer.

“In fact, even if we could justify it morally, it wouldn’t actually be affordable,”

Cameron also told the Observer that “our ability to ring-fence and protect spending on health could be at risk too”.

“This is the cold reality of leaving the EU – that’s why doctors, nurses and the boss of the NHS all say we will be stronger, safer and better-off in the EU.”

Meanwhile, Osborne has said that a vote to leave could result in cutting defence spending by approximately £1bn – £1.5bn per year.

Mr Osborne said Brexit would mean “a new dose of austerity, more years of public spending cuts”. He told the Sun on Sunday: “If you look at the numbers, the defence budget would have to be cut by between £1bn – £1.5bn.

“It’s the last thing I want to do because I want the country to stay in the European Union, but if we leave the European Union Britain is smaller and so Britain’s armed forces will be smaller and that means fewer planes and ships and personnel to defend us.

“So it is both a hit to our national economic security but also our national security.”

Scaremongering?

Ex-Cabinet minister Iain Duncan Smith, who is in favour of a Brexit, accused his party leader of a “vindictive and desperate attempt to bully and frighten the British people”.

“This is a baseless threat,” he said. “The truth is that these are policy choices and the Conservative manifesto said that protecting pensioners was a priority.

“It is now apparent that there is nothing they will not use or jettison in their efforts to keep us in the European Union.”